Oscar Pistorius has a split personality that has led to the formation of "two Oscars" – one a vulnerable and fearful person with a disability, the other a confident Olympic hero, a court has heard.

His lawyer Kenny Oldwadge revealed details of a psychological profile of the athlete that had been banned from publication by judge Thokozile Masipa the previous day.

Pistorius, 27, is accused of murdering his girlfriend, Reeva Steenkamp, at his home in February 2013. The double amputee known as the "blade runner" denies the charge, claiming he fired four gun shots in fear after mistaking her for a burglar.

Oldwadge told the high court in Pretoria, South Africa, on Thursday that a report by a clinical psychologist following Pistorius's 30-day mental health evaluation described a "split in his personality … the one a vulnerable, scared disabled person, the other a strong physical person achieving beyond expectation and finding reward for it both intra-physically and interpersonally".

Another section of the report by Dr Jonathan Scholtz elaborated on the theme : "I believe the construction of 'the two Oscars' I referred to earlier finally gelled into a final split. The one Oscar being an international superstar, more confident and feeling more in control at 1.84 metres tall. That part of him falling back on his physicality and 'never say die' attitude that had served him so well. Although not completely at ease, he felt less vulnerable in that state.

"The other Oscar being a vulnerable and fearful disabled person, at less than 1.5 metres once his prostheses were removed and he was alone at night. That part of him falling back on to his anxiety and fear, not feeling in control. With his prostheses on many people can damage him but without them he feels defenceless. 'I am stuffed without my legs on.' For this reason he acquired a weapon and even searched for one that was lighter and smaller so that he could always keep it with him."

The evidence came as Oldwadge questioned medical expert Prof Wayne Derman, who argued that Pistorius feels highly vulnerable and acted out of fear, not anger, when he shot dead Steenkamp. "Although he loathes to be pitied in any way, the hard truth is that he does not have lower legs," he said.

Echoing the notion of "two Oscars", Derman, chief medical officer of the South African Paralympic team at the 2012 London Olympics, noted the discrepancy between a sprinter crossing the finish line with raised arms and the severe limitations of being a double amputee. "You've got a paradox. Of an individual who is supremely able and an individual who is significantly disabled."

Vividly describing the daily social and physical hardships of people with disabilities, Derman added: "The saddest thing I have learned through my six years of working with athletes with disability is that disability never sleeps. It's there when you go to sleep at night and it's there when you wake up in the morning. It affects nearly every aspect of your life."